The present invention relates to a portable fluorescent tube assembly which can be manually moved and suspended about a work site to aid a user to obtain the best lighting conditions. It has been the practice to use incandescent light bulbs, suitably encased in light guards, for this purpose. Such lights are often referred to as trouble lamps, extension lights, work lights, inspection lights, and the like, and are commonly employed by mechanics and other workers who require a concentration of light in a frequently changing location.
Fluorescent lights have several advantages in use as compared with the incandescent bulbs. As an example, for the same wattage fluorescent lights usually provide more light with less glare. In the past, attempts have been made to convert portable lights such as extension lights to fluorescent tubes. However, a number of serious problems have arisen, particularly in attempting to adapt a fluorescent tube to a satisfactory portable assembly. A common complaint is that the electrical connections between a fluorescent tube and its mounting and electrical conductors are not originally, or do not long remain, sufficiently tight to provide desired electroconductivity, especially as compared to the more commonly used incandescent light bulbs. When inadequate electrical contacts occur, fluorescent tubes exhibit disproportionately high electrical resistance.
It is, of course, quite important that a fluorescent tube be firmly mounted and snugly held by its supports, especially if the tube is designed for portable use. While an incandescent bulb has a relatively large area of contact for electrical connection around its threaded base, the usual fluorescent tube has only a pair of relatively fine, fragile pins extending from opposite ends of the tube which constitute electrical terminals. In order to insure a firm and constant electrical connection with the terminal pins, prior socket connections have been quite heavy and cumbersome. In some instances, sockets used for each set of pin terminals are mounted apart facing each other as on a single bracket somewhat longer than the fluorescent tube itself. Such sockets are usually stationary and not movable with respect to each other. This restriction often limits the manner in which the fluorescent tube can be mounted and used.
Additionally, it has been the practice to mount a ballast for the fluorescent tube in-line, that is, in the electrical cord which energizes the tube. The ballast which includes a transformer is normally quite heavy. This adds to the problems of supporting and mounting the fluorescent tube itself. Further, a ballast generates heat in use and the added heat, so generated, can be a problem when adjacent to the tube and its assembly.
These structural problems become even more acute if it is desired to construct a portable fluorescent tube assembly. Portable units are much more susceptible to rough handling. The tube assembly may be dropped or, at a minimum, subject to jarring, vibration, and the like. Such mechanical shocks tend to dislodge or momentarily interrupt an electric current to the tube pins at the opposite ends of the tube and produce a high voltage arc, thereby introducing health and safety hazzards.
U.S. Pat. No. 2,691,092 to McConnell et al discloses a fluorescent work light of shock-absorbing construction in which sockets are vulcanized in the end closures in mutually laterally spaced relationship, the spacing being slightly different from the lateral spacing of the pins or terminal prongs on the fluorescent tubes. When an electrical connection is made, the lateral spring load tends to maintain the pins in much tighter contact with the sockets than is usually the case.
U.S. Pat. No. 4,088,882 to Lewis teaches a fluorescent bike lamp in which end caps are adhesively bonded to ends of the fluorescent tube to maintain the assembly in an integral condition.
U.S. Pat. No. 4,092,706 to Vest discloses a fluorescent light designed to accommodate elongation of a plastic housing due to thermal expansion of the housing to which socket supports are attached. The socket supports include a strip of metal bent into a four-legged rectangular shape. An inner leg is adapted to flex and thereby accommodate expansion and contraction.